It’s been more than a week since the two-year-old critter went under the knife.

Munchkin — who this Christmas received a leash and a Santa costume, and has a sweet tooth for white chocolate chips — started developing a mammary tumour in October, something common in female rats after they reach breeding age, Lily’s mom Kristina said.

After taking Munchkin to a pair of veterinarians, the family — including Lily, her mom, her dad Andrew Wellington, and her two six-year-old sisters Melanie and Emily Wellington — was told there was a high risk that the rat wouldn’t even wake up from anesthesia.

But one vet said he would still give surgery a try.

“One of the girls is of my own daughter’s age,” said Muhammad Afzal, with College Park Animal Hospital.

He couldn’t say no to the sisters, he said.

“Because they are so attached” to Munchkin, he said.

The family waited until after Christmas so Munchkin could receive her gifts, and to not put her at risk unnecessarily.

Then, when it had gotten to the point where she’d either have the surgery or have to be put down, the Corunna family made the drive to Sarnia.

The surgery took about an hour and Munchkin was fine.

“I love her so much and she’s such a sweet rat,” Lily said. “She means so much to me.”

Afzal had purchased an induction chamber, which helps the sedation process, specifically for Munchkin.

“It was very kind of him,” Lily’s mom said. “I’m sure he probably spent more on the equipment to perform Munchkin’s surgery than he charged us.”

The induction chamber cost about $400, he said, but can also be used for small cats and dogs.

Now Munchkin is back spending time with her family.

“She’s very snugly and gives kisses,” Lily said.

Munchkin is one of about five pet rats the sisters have had.

And there’s plenty of room for animals at their home. Their parents have two ball snakes, a pair of tarantulas from the humane society, a dog, and they’ve also fostered dogs and rescued others from kill shelters.

Now, grateful for what Afzal did, Lily said she wants to use money she received on Valentine’s Day to buy him a gift.

She even typed a letter to The Observer to thank him.

“I was extremely happy because that rat was loved as much as a human being,” she wrote. “I want to give all my thanks to Dr. Afzal.”